High solids coating and process for coating

ABSTRACT

Described is a high solids coating composition having exceptional rheological properties and appearances comprising (a) a thermosetting binder, (b) from about 0.1 to about 10 wt. % based on binder solids of solid polyurea particles prepared by the reaction of a mixture of a polyisocyanate and an amino reactant comprising a primary or secondary monoamine that optionally has a hydroxyl or ether group or both, and (c) from about 2 to about 25 wt. % on resin solids of an acrylic polymer having a number average molecular weight of from about 2000 to about 8000 and a glass transition temperature of from about 50 to about 120° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National State entry of PCT/US2012/065578, filedon Nov. 16, 2012, which claims priority to U.S. Provisional ApplicationSer. No. 61/568,919, filed on Dec. 9, 2011, the disclosures of which areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to coating compositions and coatingmethods, more particularly to automotive and industrial high solids,thermosetting coating compositions that provide good appearance andmethods for applying these coating compositions and controlling therheology of the applied coating compositions to provide good appearance.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

“High solids” is a designation given in the industrial and automotivecoatings fields to coating compositions or paints that are solventbornecompositions and have a higher nonvolatile content, such as anonvolatile content of more than about 40 weight percent (wt. %). Thenonvolatile content is determined in accordance with ASTM Test MethodD2369, in which the test sample is heated at 110° C. (230° F.) for 60minutes. Coatings manufacturers have worked to reduce solvent content ofindustrial and automotive coating compositions for decades and have overthe years developed various higher solids technologies. The solidscontent that can be achieved for a particular coating compositiondepends to a certain extent on the type of coating it is and theproperties it must have on the substrate. It is generally understoodthat, while very low molecular weight resins allow less solvent to beadded, one may not be able to achieve the necessary application andcured coating properties using such low molecular weight resins. Asanother example, one is generally able to make a sprayable clearcoatcoating composition with a higher solids content than a sprayablepigmented coating composition. The dispersed pigment tends to increaseviscosity of the coating so that more solvent must be added to obtain asuitable spray viscosity (that is, a suitable viscosity for applicationby spraying the coating onto the substrate).

The color and appearance of the coating can be of primary importance, asis true, for example, for automotive topcoat coatings. The color forthese topcoats are provided by monocoat topcoat coatings, which are asingle-layer topcoat, or basecoat coatings, which are used as the colorlayer under a clearcoat coating layer in a composite two-layer topcoat.Special effect colors, e.g. metallic and pearlescent colors and coatingswith color-variable pigments, present an added challenge for thesetopcoat coatings. special effect flake pigments. Special effect pigmentsare those that can produce a gonioapparent effect in a coating layer.For example, the American Society of Testing Methods (ASTM) documentF284 defines metallic as “pertaining to the appearance of agonioapparent material containing metal flake.” Metallic basecoat colorsmay be produced using metallic flake pigments like aluminum flakepigments including colored aluminum flake pigment, copper flakepigments, zinc flake pigments, stainless steel flake pigments, andbronze flake pigments and/or using pearlescent flake pigments includingtreated micas like titanium dioxide-coated mica pigments and ironoxide-coated mica pigments to give the coatings a different appearanceor color when viewed at different angles. Rheology control is neededduring application of these coating compositions to allow the flakes toorient parallel to the face of the film for optimum gonioapparenteffect. The flake pigments that produce metallic and pearlescent colorsand colors that vary with viewing angle must, during drying of theapplied coating layer, achieve an orientation substantially parallel tothe substrate to provide the optimum desired metallic, pearlescent, orcolor-variable effect. High solids coating compositions with thesepigments, grouped generally as “metallic” coating compositions, have notprovided the outstanding difference in brightness between face (viewedhead-on) and flop (viewed at an oblique angle) that can be achieved forlow solids, high-solvent-content coatings. Obtaining proper rheologycontrol during application and cure of pigmented high solids topcoats,especially when using high solids metallic topcoat compositions, whilecontinuing to meet the stringent performance requirements for suchcoatings remains a demanding task.

Unpigmented clearcoat topcoat coatings require some kind of rheologycontrol agent to allow a extremely high degree of surface smoothness toachieve a high distinctness of image (DOI). Clearcoat and monocoattopcoat coating layers are generally relatively thick, typically between1.5 and 3 mils (about 38 to about 76 microns) thick for both appearanceand protection. In coating automotive vehicle bodies, the topcoat isapplied to both horizontal and vertical surfaces. Manufacturing economyconstraints require this relatively thick clearcoat or monocoat topcoatlayer be applied in a minimum of time and manufacturing floor space;accordingly, the clearcoat or monocoat coating composition is appliedthickly onto the substrate, leaving in the coating layer a significantamount of solvent that must be evaporated before bake, during a “flash”period of solvent evaporation, and during bake of the topcoat. Whilethere is less of a problem on horizontal surfaces with applying a ratherthick coating layer leaving significant solvent content in the layer, onvertical surfaces a topcoat layer with still significant solvent contentmay flow too much, causing sags to develop in the coating layer. Saggingmay also occur in other areas where the substrate is not flathorizontally, for example along character lines, gutters, or channels ofan automotive vehicle body. Thus, rheology control is important for thisreason as well.

SUMMARY

We have discoveredDescribed are metallic and other high solids coatingcompositions having exceptional rheological properties and methods forobtaining better rheology control in metallic and other high solidscoating compositions and for preparing and applying such high solidscoating compositions to produce metallic or other coatings withexceptional appearance.

Further described is a high solids coating composition containing (a) athermosetting binder, (b) from about 0.1 to about 10 wt. % based onbinder solids of solid polyurea particles prepared by the reaction of apolyisocyanate and an amino reactant comprising a monoamine, and (c)from about 2 to about 25 wt. % on binder solids of an acrylic polymerhaving a number average molecular weight of from about 2000 to about8000 and a glass transition temperature of from about 50 to about 120°C. The solid polyurea particles prepared by the reaction of apolyisocyanate and an amino reactant comprising a monoamine will bereferred to as “solid polyurea particles.” The acrylic polymer havingthese features will be referred to as “low molecular weight, high Tgacrylic polymer.”

In various embodiments, the high solids coating compositions are topcoatcompositions. In various embodiments, the high solids coatingcomposition further comprises a pigment, particularly basecoat andmonocoat topcoat compositions. Among the embodiments further comprisinga pigment are high solids coating compositions comprising a flakepigment, particularly basecoat and monocoat topcoat compositions.

In another aspect, a method is disclosed of spray applying the highsolids coating composition containing a thermosetting binder, solid ureaparticles, and the low molecular weight, high Tg acrylic polymer in alayer on a substrate, then curing the applied coating composition toproduce a cured coating on the substrate.

Also described is a method of coating a substrate that includes applyingat least one primer coating composition to form a primer layer, at leastone basecoat composition to form a basecoat layer, and at least oneclearcoat composition to form a clearcoat layer to a substrate; wherethe basecoat composition is applied when the primer layer is uncured;wherein the basecoat composition is the high solids coating compositioncomprising a thermosetting binder, solid urea particles, and the lowmolecular weight, high Tg acrylic polymer. In various embodiments, thebasecoat composition comprises a flake pigment or a combination of flakepigments.

Further described is a method of coating a substrate that includesapplying at least one primer coating composition to form a primer layer,at least one basecoat composition to form a basecoat layer, and at leastone clearcoat composition to form a clearcoat layer to a substrate;wherein the clearcoat composition is applied when the basecoat layer isuncured; and wherein the basecoat composition is the high solids coatingcomposition comprising a thermosetting binder, solid urea particles, andthe low molecular weight, high Tg acrylic polymer. In variousembodiments, the basecoat composition comprises a flake pigment or acombination of flake pigments.

Yet further described is a method of coating a substrate that includesapplying at least one primer coating composition to form a primer layer,at least one basecoat composition to form a basecoat layer, and at leastone clearcoat composition to form a clearcoat layer to a substrate;where the basecoat composition is applied when the primer layer isuncured and the clearcoat composition is applied when the basecoat layeris uncured; and wherein the basecoat composition is the high solidscoating composition comprising a thermosetting binder, solid ureaparticles, and the low molecular weight, high Tg acrylic polymer. Invarious embodiments, the basecoat composition comprises a flake pigmentor a combination of flake pigments.

Additionally described is a method for obtaining better rheology controlin metallic and other high solids coating compositions in which aneffective amount of a rheology control additive package including solidpolyurea particles and a low molecular weight, high Tg acrylic polymeris included in the high solids coating compositions.

In a method of preparing a high solids coating composition, a binderresin including solid polyurea particles is combined with a lowmolecular weight, high Tg acrylic polymer. The binder is thermosetting.In various embodiments, a flake pigment or a combination of flakepigments is included in the high solids coating composition. The highsolids coating composition is applied in a topcoat layer on a substrate(as a monocoat topcoat layer or as a basecoat layer of abasecoat-clearcoat composite topcoat) and cured to provide a coatingwith exceptional appearance on the substrate. A high solids coatingcomposition including a flake pigment is applied in a layer on asubstrate and cured to provide an effect coating with exceptional effectappearance on the substrate, where the effect is a metallic effect whena metallic pigment is used, a pearlescent effect when a pearlescentpigment is used, and a color-variable effect when a color-variablepigment is used.

In various embodiment, the high solids coating composition includes arheology control agent in addition to the solid polyurea particles andthe low molecular weight, high Tg acrylic polymer. In variousembodiments, the high solids coating composition includes a furtherrheology control agent selected from cellulose mixed esters other thanthe low molecular weight cellulose mixed ester, microgel rheologycontrol agents such as crosslinked acrylic polymer microparticles, waxrheology control agents, inorganic phyllosilicates, and fumed silicas.In various embodiments, the high solids coating composition furtherincludes from about 0.1 to about 3% by weight based on binder weight ofan additional rheology control agent selected from cellulose mixedesters, crosslinked acrylic polymeric microparticles, inorganicphyllosilicates, and fumed silicas.

The disclosed compositions and methods provide coatings with enhancedappearance and particularly enhanced special effect appearance forcoatings including flake pigments. The disclosed compositions havesuperior rheological properties during application of the coatingcompositions that is provided by the combination of the two rheologycontrol agents, the solid polyurea particles and the low molecularweight, high Tg acrylic polymer. This combination of rheology controlagents provides unexpected synergy, resulting in excellent colorconsistency and metallic appearance in high solids basecoats andtopcoats, while allowing the coating composition's solids content toremain high. In light of the prior art it was surprising andunforeseeable that the disclosed coating compositions and methods of theinvention could provide improved rheology control and metallicappearance of colored, high solids topcoats without any decrease instability, durability, nonvolatile content, and other performancerequirements. The synergistic improvement in color consistency andmetallic appearance could not have been predicted based upon performanceof the two rheology control agents individually or in view of earlierknown rheology control agent combinations.

In describing these coating compositions and methods, certain terms areused that have the following meanings.

For convenience, “resin” is used in this disclosure to encompass resin,oligomer, and polymer. “Binder” refers to the film-forming components ofthe coating composition. Thus, resins, crosslinkers, and otherfilm-formers are part of the binder, but solvents, pigments, additiveslike antioxidants, HALS, UV absorbers, leveling agents, and the like arenot part of the binder. A “thermosetting” binder refers to curable orcrosslinkable binders.

Number average molecular weight and weight average molecular weight aredetermined by gel permeation chromatography of a sample dissolved intetrahydrofuran using polystyrene or poly(methyl methacrylate)standards. “Polydispersity” is the ratio of weight average molecularweight over number average molecular weight.

Glass transition temperature is measured by Differential Scanningcalorimetry or calculated using the Fox Equation, in which thereciprocal of the glass transition temperature (in degrees Kelvin) ofthe copolymer is the summation for all different copolymerized monomersof the reciprocal of the glass transition temperature (in degreesKelvin) for a homopolymer of each monomer multiplied by the weightfraction of that monomer in the copolymer. (See T. G. Fox, Bull. Am.Phys. Soc. 1 (1956) 123.) The glass transition temperatures ofhomopolymers for the purposes are reported in literature, particularlyin the “Polymer Handbook”, edited by J. Brandrup et al.,Wiley-Interscience, (currently in a fourth edition republished in 2003)or, if unavailable in literature, the Tg of a homopolymer may bemeasured by differential scanning colorimetry (DSC).

“Pigment” refers to colorants that are insoluble in the coatingcomposition. “Flake pigment” refers to pigments that are in the form offlakes or thin platelets, such as mica-based pigments and metal flakepigments like aluminum pigment.

“Metal travel” and “travel” both refer to a difference in brightness ofa coating when viewed head-on (“face”) and when viewed at an obliqueangle (“flop”). Travel can be measured in different ways. One way ismetal flop index, MFI, which is determined with a spectrophotometeraccording to the following formula:MFI=50×(L25−L75)/L75,where L25 and L75 are the measurement of lightness L taken at angles of25° and 75°, respectively, from the plane of the coating layer. A highermetal flop index number indicates more travel.

“A,” “an,” “the,” “at least one,” and “one or more” are usedinterchangeably to indicate that at least one of the item is present; aplurality of such items may be present. Other than in the workingexamples provides at the end of the detailed description, all numericalvalues of parameters (e.g., of quantities or conditions) in thisspecification, including the appended claims, are to be understood asbeing modified in all instances by the term “about” whether or not“about” actually appears before the numerical value. “About” indicatesthat the stated numerical value allows some slight imprecision (withsome approach to exactness in the value; approximately or reasonablyclose to the value; nearly). If the imprecision provided by “about” isnot otherwise understood in the art with this ordinary meaning, then“about” as used herein indicates at least variations that may arise fromordinary methods of measuring and using such parameters. In addition,disclosure of ranges includes disclosure of all values and furtherdivided ranges within the entire range.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Thedetails, examples and preferences provided above in relation to anyparticular one or more of the stated aspects of the present invention,and described and exemplified below in relation to any particular one ormore of the stated aspects of the present invention, apply equally toall aspects of the present invention.

The high solids coating composition includes the thermosetting binder,the solid polyurea particles, and the low molecular weight, high Tgacrylic polymer. The solid polyurea particles are insoluble in thebinder and are the reaction product of a reaction product comprising apolyisocyanate and a monoamine.

The solid polyurea particles may be those described, for example, in USPatent Publication No. US 2004/0158022, U.S. Pat. Nos. 4,311,622 and4,888,373 European Patent Publications No. EP 0 198 519 and EP 0 192304. The monoamine may be a primary or secondary amine and may includehydroxyl or ether groups. The coating composition may include 0.1 to 10percent by weight of the solid polyurea particles, based on total binderweight. The solid polyurea particles may have an average particle sizeof from 0.01 to 50 micrometers.

In general the solid polyurea particles may be prepared by reacting amixture including a polyisocyanate compound or combination ofpolyisocyanate compounds and a monoamine or combination of monoamines,and that may include other, optional reactants. The monoamine may be aprimary or secondary monoamine, which may include hydroxyl or ethergroups. The reaction mixture may further include water, a polyamine, amonoisocyanate, or a combination of these optional further reactants. Invarious embodiments, a polyamine with primary and/or secondary aminegroups or a combination of such polyamines and/or water is includedalong with the monoamine or combination of monoamines as described inthe reaction mixture with the polyisocyanate or combination ofpolyisocyanates. In various embodiments, the solid polyurea particlesmay be prepared by reacting a mixture including a polyisocyanatecompound, a monoisocyanate compound, a monoamine, and a polyamine.

The polyisocyanate or polyisocyanates may be selected from any organiccompound having at least two isocyanate groups per molecule, includingnot only those in which the isocyanate groups are attached to ahydrocarbon radical but also those in which the isocyanate groups areattached to a radical including a heteroatom such as oxygen or nitrogen,for example as part of ester groups, ether groups, tertiary aminegroups, urea groups, urethane groups, biurets, isocyanurates,allophanate groups, uretdione groups, and the like, as well ascombinations of these. Any suitable diisocyanate may be used for thepreparation of the solid polyurea particles such as an aliphatic oraraliphatic or cycloaliphatic or aromatic diisocyanate. The diisocyanateusually contains from 3 to 40, and in various embodiments thediisocyanate may contain from 4 to 20, from 5 to 24, or from 6 to 18,carbon atoms. In certain specific embodiments, a symmetrical aliphaticor cycloaliphatic diisocyanate is used. Nonlimiting examples of suitablediisocyanates include trimethylene-1,3-diisocyanate,tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate,ω,ωα-dipropylether diisocyanate, cyclohexyl-1,4-diisocyanate,dicyclohexylmethane-4,4′-diisocyanate,1,5-dimethyl-2,4-bis(isocyanatomethyl)benzene,1,5-dimethyl-2,4-bis(isocyanatoethyl)benzene,1,3,5-trimethyl-2,4-bis(isocyanatomethyl)benzene,1,3,5-triethyl-2,4-bis(isocyanatomethyl)benzene, isophoronediisocyanate, dicyclohexyldimethylmethane-4,4′-diisocyanate, 2,4-toluenediisocyanate, 2,6-toluene diisocyanates,diphenylmethane-4,4′-diisocyanate, m-tetramethylxylene diisocyanate,naphthalene-1,5-diisocyanate, p-phenylene diisocyanate,methyl-2,6-diisocyanatohexanoate; isocyanurates, biurets, allophanates,and uretdiones of these; and combinations of any plurality of these. Invarious embodiments, it is advantageous to use an aliphatic orhomocyclic diisocyanate containing 6-9 carbon atoms, such ascyclohexyl-1,4-diisocyanate, toluene diisocyanates and hexamethylenediisocyanate, isocyanurates of these compounds, and combinations ofthese.

Optionally, the mixture may include a monoisocyanate such as octylisocyanate, cyclohexyl isocyanate, butyl isocyanate, hexyl isocyanate,decyl isocyanate, undecyl isocyanate, and combinations of these.

The second component of the reaction mixture used in the preparation ofthe solid polyurea particles is a monoamine, which may have a hydroxylgroup or an ether group. In various embodiments, the monoamine may havenot more than about 24 carbon atoms and more particularly not more thanabout 12 carbon atoms. Specific, nonlimiting examples of suitablemonoamines without hydroxyl or ether groups that may be used includebenzylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine,isobutylamine, tert-butylamine, n-pentylamine, 1-methylbutylamine,2-methylbutylamine, 1-ethylpropylamine, N-ethylbutylamine,N-methylbutylamine, n-hexylamine, n-octylamine, iso-nonanylamine,iso-tridecylamine, n-decylamine, stearylamine, and combinations ofthese. In various embodiments, monoamines having 1-4 aliphatic carbonatoms such as benzylamine, propylamine, and tert-butylamine are used.Specific, nonlimiting examples of suitable monoamines having hydroxylgroups that may be used include 2-aminoethanol, 1-aminoethanol,2-aminopropanol, 3-aminopropanol, 1-amino-2-propanol, 2-amino-2-methylpropanol, 2-aminobutanol, 5-aminopentanol,3-amino-2,2-dimethyl-1-propanol, 2-(2-aminoethoxy)ethanol,2-amino-1-butanol, 2-amino-2-methyl-1-propanol, andpolyhydroxymonoamines such as 2-amino-2-methyl-1,3-propanediol,2-amino-2-ethyl-1,3-propanediol, diethanolamine, and combinations ofthese. The monoamine may also have an ether linkage. Specific,nonlimiting examples of such alkoxyamines include 2-methoxyethylamine,2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxymethylpropylamine,1,1-dimethoxy-2 propylamine, 3-ethoxy-1-propylamine,3-butoxy-1-propylamine, 3-(2-ethylhexyloxy)-1-propylamine,3-tridecyloxypropylamine, 3-stearyloxypropylamine, p-methoxybenzylamine,3,4-dimethoxybenzylamine, p-methoxyphenylethylamine,3,4-dimethoxyphenyl-ethylamine, 9-phenoxy-4,7-dioxanon-1-amine,2-methyl-4-methoxyaniline, 2,5-dimethoxy-aniline, furfurylamine,tetrahydrofurfurylamine, 2-(4-morpholinyl)ethylamine,4-(3-aminopropyl)morpholine, 2,2′-aminoethoxyethanol, and combinationsof these. Mixtures of one or more monoamines, with and without hydroxylor ether groups, may be used in any combination. In certain embodiments,the monoamine is or includes a primary monoamine such as an aliphaticmonoamine with 1 to about 6 carbon atoms. In certain embodiments, themonoamine may be selected from benzylamine, ethylamine, n-propylamine,isopropylamine, n-butylamine, isobutylamine, tert-butylamine,2-aminoethanol, 1-aminoethanol, 2-aminopropanol, 3-aminopropanol,1-amino-2-propanol, 2-amino-2-methyl propanol, 2-methoxyethylamine,2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxymethylpropylamine,and combinations of these.

In further embodiments, a polyamine may be included in the reactionmixture forming the solid polyurea particles. The polyamine in certainembodiments is a diamine in which the amine groups may be primary aminegroups. Nonlimiting examples of suitable polyamines include aliphatic,cycloaliphatic, aromatic, aliphatic-aromatic, cycloaliphatic-aromatic,and aliphatic-cycloaliphatic polyamines, in which the nomenclature isused in a way that “aliphatic-aromatic polyamine” indicates a polyaminein which at least one amino group is attached to an aliphatic group andat least one amino group is attached to an aromatic group and thenomenclature is applied accordingly for the other types of polyaminesmentioned.

Further examples of other solid polyurea particles that may be usedinclude those disclosed in Baumgart et al., U.S. Patent ApplicationPublication No. 2004/0158022 and in Lenges et al., U.S. Pat. No.7,741,510, the relevant contents of both being incorporated herein byreference.

In certain embodiments, the reaction mixture is or includes a monoamineselected from benzylamine, propylamine, and tert-butylamine,2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxy-1-propylamine,1-methoxymethylpropylamine, 2-aminoethanol, 1-aminoethanol,2-aminopropanol, 3-aminopropanol, 1-amino-2-propanol, 2-amino-2-methylpropanol, 2-aminobutanol, p-methoxybenzylamine,3,4-dimethoxybenzylamine, and combinations of these and a polyisocyanateselected from cyclohexyl-1,4-diisocyanate, toluene diisocyanates andhexamethylene diisocyanate, isocyanurates of these compounds, andcombinations of these compounds.

In the reaction between the diisocyanate and the monoamine, generallyeither the diisocyanate or the monoamine may be used in excess relativeto the stoichiometric amount. For example, the ratio of the equivalentsof amino groups of the monoamine and any optional polyamine and water tothe equivalents of isocyanate groups of the polyisocyanate and anyoptional monoisocyanate may be from about 0.7 to about 1.5 equivalentsamine for each equivalent isocyanate, or from about 0.9 to about 1.2equivalents amine for each equivalent isocyanate, or from about 0.95 toabout 1.1 equivalents amine for each equivalent isocyanate, orapproaching 1:1 even more closely. In various embodiments, a monoamineor a combination of monoamines may be reacted with a polyisocyanate or acombination of polyisocyanates, with the reactants being apportioned sothat the ratio of equivalents between amino groups and isocyanate groupsfrom about 1.2 to about 0.4. In various embodiments the ratio ofequivalents between amino groups and isocyanate groups from about 1.0 toabout 0.8. Aliphatic monoamines and polyisocyanates may be preferredwhen the solid polyurea particles are used in certain coatingcompositions.

When a polyamine is included, the reactants may be apportioned so thatthe ratio of equivalents between amino groups to isocyanate groups fromabout 1:2 to about 2:1, which may in various embodiments be about 1:1.8to about 1.8:1, 1:1.6 to about 1.6:1, 1:1.4 to about 1.4:1, or 1:1.2 toabout 1.2:1. In the reaction forming the solid polyurea particles, theratio of equivalents of amine groups from a polyamine (when included) toamine groups from a monoamine may be from about 4:1 to about 1:2; invarious particular embodiments, the ratio of equivalents of amine groupsfrom a polyamine to amine groups from a monoamine may be from about 3:1to about 1:1, from about 2:1 to about 1:1, from about 1.5:1 to about1:1, or from about 1.2:1 to about 1:1.

The reaction between the diisocyanate and the monoamine may generally becarried out in any way by combining the reaction components, optionallyat elevated temperature. For example, the reaction may be carried out inan inert atmosphere at a temperature in the range of from about 10° to150° C., or in the range of 20° to 80° C. Generally, the diisocyanateshould be added to the monoamine, which may be done in several steps, ifdesired.

The reaction may optionally be carried out in the presence of an inertorganic solvent, such as for example, acetone, methyl isobutyl ketone,benzene, toluene, xylene, or an aliphatic hydrocarbon such as petroleumether, or may optionally be carried out in the presence of a binderresin. The binder may be any that is suitable for topcoat or basecoatcoating compositions. Nonlimiting, suitable examples that may bementioned include polyesters, polyurethanes, including those preparedusing polyester diols or polyether diols as monomers, acrylic resins andother polyvinyl resins, epoxy resins, alkyds, unsaturated oligomers andresins, aminoplasts, polyepoxides, and polycarboxylic acid or anhydrideoligomers and polymers. In various embodiments, the solid polyureaparticles are formed in a polyester, polyurethane, or acrylic resin orcombination of such resins. When carried out in the presence of anorganic solvent, the procedure may be for the amine component to beadded to one or a mixture of more than one organic solvent and then toadd the polyisocyanate component as quickly as possible and with veryvigorous stirring. When carried out in the presence of a binder resin, amixture of the binder resin and the polyisocyanate may be mixed with amixture of the binder resin and the monoamine. The mixing operation maybe carried out in any convenient manner, with the reactants beingvigorously stirred. In an embodiment of this method the binder is mixedwith such amounts of the polyisocyanate and the monoamine that uponconclusion of the reaction there is obtained a mixture to be used asmaster batch of the solid polyurea particles having from about 1 toabout 20% by weight of the solid polyurea particles and from about 80 toabout 99% by weight of the binder resin or from about 1 to about 10% byweight of the solid polyurea particles and from about 90 to about 99% byweight of the binder, based on the combined weights of binder and solidpolyurea particles. These weight ratios may result in obtaining amixture which can very readily be homogeneously mixed with the binder tobe employed in the preparation of the coating composition. The bindersin the coating composition and in the master batch of the solid polyureaparticles may be of the same or of different composition. In one or moreembodiments, in this “in situ” preparation the reaction is carried outin an atmosphere of inert gas at a temperature in the range of 20° to80° C., in which case first the monoamine is added to the binder and,after the mixture has been homogenized, the polyisocyanate is slowlyadded to the mixture, with stirring.

In certain embodiments, if the solid polyurea particles are not preparedin situ in the binder, the two components of the thixotropic coatingcomposition can be mixed by melting the solid polyurea particles at atemperature in the range of 80° to 200° C. in the presence of thebinder, as a result of which a homogeneous mixture is obtained. Afterthe mixture has been cooled to room temperature, the solid polyureaparticles form a dispersion in the binder.

In various embodiments, the coating composition includes up to about 10%or about 0.1% to about 5% or about 0.2% to about 5% by weight of thesolid polyurea particles based on the total binder weight. The solidpolyurea particles may be added in a composition having from about 15wt. % to about 50 wt. % or from about 20 wt. % to about 40 wt. % of thecombined weights of a binder resin and solid polyurea particles preparedin the binder resin.

The solid polyurea particles in the coating compositions generally havean average particle size of from about 0.01 to about 50 micrometers, orin certain embodiments from about 0.1 to about 20 micrometers or about 3to about 17 micrometers. The average particle size may be determined invarious ways, for example using a Coulter counter, laser diffraction(also known as laser light scattering), or even, in a more generalsense, using a Hegman fineness-of-grind gauge.

The disclosed high solids coating composition also includes the lowmolecular weight, high Tg acrylic polymer. The high solids coatingcomposition includes from about 2 to about 25 wt. % on total binderweight of a low molecular weight, high Tg acrylic polymer. In variousembodiments, the high solids coating composition includes from about 5to about 20 wt. % or from about 5 to about 13 wt. % or from about 6 toabout 10 wt. % on total binder weight of a low molecular weight, high Tgacrylic polymer.

The low molecular weight, high Tg acrylic polymer has a number averagemolecular weight of from about 2000 to about 8000. In variousembodiments, the low molecular weight, high Tg acrylic polymer may havea number average molecular weight of from about 4000 to about 8000, andvarious coating compositions may use a low molecular weight, high Tgacrylic polymer having a number average molecular weight of from about5500 to about 7500. In various embodiments the low molecular weight,high Tg acrylic polymer may have a weight average molecular weight offrom about 5000 to about 25,000, particularly from about 10,000 to about22,000 and a polydispersity of from about 2.0 to about 4, particularlyfrom about 2.5 to about 3.5.

The low molecular weight, high Tg acrylic polymer has a glass transitiontemperature of from about 50 to about 120° C. in various embodiments,the low molecular weight, high Tg acrylic polymer has a glass transitiontemperature of from about 60 to about 110° C., from about 65 to about100° C., or from about 70 to about 90° C. The Tg may be is measured byDifferential Scanning calorimetry or calculated using the Fox Equation,in which the reciprocal of the glass transition temperature (in degreesKelvin) of the copolymer is the summation for all differentcopolymerized monomers of the reciprocal of the glass transitiontemperature (in degrees Kelvin) for a homopolymer of each monomermultiplied by the weight fraction of that monomer in the copolymer.Although there may be small variations between the glass transitiontemperatures determined by these two methods for the low molecularweight, high Tg acrylic polymer, such small variations are nosignificant for the use of the low molecular weight, high Tg acrylicpolymer in the high solids coatings as disclosed and in the methods asdisclosed.

The low molecular weight, high Tg acrylic polymer may have functionalgroups reactive with another component of the high solids coatingcomposition during curing of the coating. In one or more embodiments,the acrylic polymer low molecular weight, high Tg acrylic polymer hasactive hydrogen functionality. Nonlimiting examples of such activehydrogen functionality include hydroxyl and carbamate groups andcombinations of these. The term “carbamate” refers to a group having astructure

in which R is H or alkyl. In one or more embodiments, R is H or alkyl offrom 1 to about 4 carbon atoms, and more specifically R is H. Furtherexamples of reactive functional groups are those described below asexamples of polymer functional groups for the thermosettable resinscurable with a crosslinking agent.

Suitable hydroxyl-functional, low molecular weight, high Tg acrylicresins may be prepared by polymerizing one or more hydroxyl-functional,ethylenically unsaturated monomers with one or more other ethylenicallyunsaturated monomers. Suitable examples of hydroxy-functionalethylenically unsaturated monomers include hydroxy alkyl esters ofacrylic or methacrylic acid. (In the context of this description, theterm “(meth)acrylate” will be used to indicate that both themethacrylate and acrylate esters are included.) Nonlimiting examples ofhydroxyl-functional monomers include hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylates, hydroxybutyl(meth)acrylates,hydroxyhexyl(meth)acrylates, other hydroxyalkyl(meth)acrylates havingbranched or linear alkyl groups of up to about 10 carbons, and mixturesof these. Generally, at least about 5% by weight hydroxyl-functionalmonomer is included in the polymer. Example embodiments include up toabout 15% by weight hydroxyl-functional monomer in the polymer. Incertain embodiments, a hydroxyl-functional, low molecular weight, highTg acrylic polymer polymerized from hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylates, and mixtures of these may be used. Theperson skilled in the art will appreciate that hydroxyl groups can begenerated by other means, such as, for example, the ring opening of aglycidyl group, for example from glycidyl methacrylate, by an organicacid or an amine. Hydroxyl functionality may also be introduced throughthio-alcohol compounds, including, without limitation,3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol,1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol,2-mercaptobenzyl alcohol, 3-mercapto-1,2-proanediol,4-mercapto-1-butanol, and combinations of these. Any of these methodsmay be used to prepare a useful hydroxyl-functional acrylic polymer.

Suitable carbamate-functional, low molecular weight, high Tg acrylicresins may be prepared by polymerizing one or more ethylenicallyunsaturated monomers having carbamate functionality in the ester portionof the monomer. Such monomers are well known in the art and aredescribed, for example in U.S. Pat. Nos. 3,479,328, 3,674,838,4,126,747, 4,279,833, and 4,340,497, 5,356,669, and WO 94/10211, thedisclosures of which are incorporated herein by reference. One method ofsynthesizing such a monomer involves reaction of a hydroxy ester withurea to form the carbamyloxy carboxylate (i.e., carbamate-modifiedacrylic monomer). Another method of synthesis reacts an α,β-unsaturatedacid ester with a hydroxy carbamate ester to form the carbamyloxycarboxylate. Yet another technique involves formation of a hydroxyalkylcarbamate by reacting a primary or secondary amine or diamine with acyclic carbonate such as ethylene carbonate. The hydroxyl group on thehydroxyalkyl carbamate is then esterified by reaction with acrylic ormethacrylic acid to form the monomer. Other methods of preparingcarbamate-modified acrylic monomers are described in the art, and can beutilized as well. The acrylic monomer can then be polymerized along withother ethylenically unsaturated monomers by techniques well known in theart.

An alternative route for preparing the carbamate-functional, lowmolecular weight, high Tg acrylic resins is to react an already-formedacrylic polymer with another component to form a carbamate-functionalgroup appended to the polymer backbone, as described in U.S. Pat. No.4,758,632. One technique for preparing such polymers involves thermallydecomposing urea (to give off ammonia and HNCO) in the presence of ahydroxy-functional acrylic polymer to form a carbamate-functionalpolymer. Another technique involves reacting the hydroxyl group of ahydroxyalkyl carbamate with the isocyanate group of anisocyanate-functional polymer to form the carbamate-functional polymer.Isocyanate-functional acrylics are known in the art and are described,for example in U.S. Pat. No. 4,301,257, the disclosure of which isincorporated herein by reference. Isocyanate vinyl monomers are wellknown in the art and include unsaturated m-tetramethyl xyleneisocyanate. Yet another technique is to react the cyclic carbonate groupon a cyclic carbonate-functional acrylic with ammonia in order to formthe carbamate-functional acrylic. Cyclic carbonate-functional acrylicpolymers are known in the art and are described, for example, in U.S.Pat. No. 2,979,514, the disclosure of which is incorporated herein byreference. Another technique is to “transcarbamylate” ahydroxy-functional polymer with an alkyl carbamate. A more difficult,but feasible way of preparing the polymer would be to trans-esterifywith a hydroxyalkyl carbamate.

Examples of suitable comonomers that may be polymerized along with theethylenically unsaturated monomer having the crosslinkable functionalityor the functionality that will be derivatized to provide thecrosslinkable functionality include, without limitation,α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5carbon atoms such as acrylic, methacrylic, and crotonic acids and thealkyl and cycloalkyl esters, nitriles, and amides of acrylic acid,methacrylic acid, and crotonic acid; α,β-ethylenically unsaturateddicarboxylic acids containing 4 to 6 carbon atoms and the anhydrides,monoesters, and diesters of those acids; vinyl esters, vinyl ethers,vinyl ketones, and aromatic or heterocyclic aliphatic vinyl compounds.Representative examples of suitable esters of acrylic, methacrylic, andcrotonic acids include, without limitation, those esters from reactionwith saturated aliphatic alcohols containing 1 to 20 carbon atoms, suchas methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl,hexyl, 2-ethylhexyl, dodecyl, cyclohexyl, alkyl-substituted cyclohexyl,alkanol-substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butylcyclohexyl, 4-cyclohexyl-1-butyl, 2-tert-butyl cyclohexyl, 4-tert-butylcyclohexyl, 3,3,5,5,-tetramethyl cyclohexyl, tetrahydrofurfuryl,isobornyl, lauryl, and stearyl acrylates, methacrylates, and crotonates;unsaturated dialkanoic acids and anhydrides such as fumaric, maleic,itaconic acids and anhydrides and their mono- and diesters with alcoholssuch as methanol, ethanol, propanol, isopropanol, butanol, isobutanol,and tert-butanol, like maleic anhydride, maleic acid dimethyl ester andmaleic acid monohexyl ester; vinyl acetate, vinyl propionate, vinylethyl ether, and vinyl ethyl ketone; styrene, α-methyl styrene, vinyltoluene, 2-vinyl pyrrolidone, and p-tert-butylstyrene. The co-monomersmay be used in any desired combination to obtain that provides therequired glass transition temperature and coating properties.

In various embodiments, the low molecular weight, high Tg acrylic resinacrylic polymer is polymerized using one or more cycloaliphaticmonomers. Nonlimiting, suitable examples of cycloaliphatic monomersinclude cyclohexyl(meth)acrylate, (meth)acrylate esters ofalkyl-substituted cyclohexanol, and (meth)acrylate esters ofalkanol-substituted cyclohexane, such as 2-tert-butyl and 4-tert-butylcyclohexyl(meth)acrylate, 4-cyclohexyl-1-butyl(meth)acrylate, and3,3,5,5,-tetramethyl cyclohexyl(meth)acrylate; isobornyl(meth)acrylate;isomenthyl(meth)acrylate; cyclopentyl(meth)acrylate, (meth)acrylateesters of alkyl-substituted cyclopentanols, and (meth)acrylate esters ofalkanol substituted cyclopentanes; adamantanyl(meth)acrylates;cyclododecyl(meth)acrylate; cycloundecanemethyl(meth)acrylate;dicyclohexylmethyl(meth)acrylate; cyclododecanemethyl (meth)acrylate;menthyl(meth)acrylate; and so on, as well as combinations of these. Insome embodiments cyclohexyl(meth)acrylate, isobornyl(meth)acrylate orboth are used. The cycloaliphatic monomer units are included in theacrylic polymer in amounts of at least about 45% by weight, specificallyat least about 60% by weight, and more specifically at least about 65%by weight of the polymer. It is advantageous for the cycloaliphaticmonomer units to be included in the low molecular weight, high Tgacrylic resins in amounts of up to about 85% by weight, particularly upto about 80% by weight, and especially up to about 75% by weight of thepolymer.

The acrylic polymer may be prepared using conventional techniques, suchas by heating the monomers in the presence of a polymerizationinitiating agent and optionally a chain transfer agent. In one or moreembodiments, the polymerization is carried out in solution, although itis also possible to polymerize the acrylic polymer in bulk or as anemulsion.

Typical initiators are organic peroxides such as dialkyl peroxides suchas di-t-butyl peroxide, peroxyesters such as t-butyl peroxy2-ethylhexanoate, and t-butyl peracetate, peroxydicarbonates, diacylperoxides, hydroperoxides such as t-butyl hydroperoxide, andperoxyketals; azo compounds such as 2,2′azobis(2-methylbutanenitrile)and 1,1′-azobis(cyclohexanecarbonitrile); and combinations of these.Typical chain transfer agents are mercaptans such as octyl mercaptan, n-or tert-dodecyl mercaptan; halogenated compounds, thiosalicylic acid,mercaptoacetic acid, mercaptoethanol and the other thiol alcoholsalready mentioned, and dimeric alpha-methyl styrene.

The reaction is usually carried out at temperatures from about 20° C. toabout 200° C. The reaction may conveniently be done at the temperatureat which the solvent or solvent mixture refluxes, although with propercontrol a temperature below the reflux may be maintained. In one or moreembodiments, the initiator should be chosen to match the temperature atwhich the reaction is carried out, so that the half-life of theinitiator at that temperature should be no more than about thirtyminutes. Further details of addition polymerization generally and ofpolymerization of mixtures including (meth)acrylate monomers is readilyavailable in the polymer art.

The rheological behavior of the high solids coating composition, andthus the appearance of coated substrates prepared using the high solidscoating composition, depends on the content of solid polyurea particlesand low molecular weight cellulose mixed esters and the nature of thesolid polyurea particles, the low molecular weight cellulose mixedester, and the binder. Generally, the solid polyurea particles may beused in an amount of 0.1 to 10 percent by weight, or in variousembodiments from about 0.2 to about 9 percent by weight, or from about0.3 to about 8 percent by weight, or from about 0.4 to about 7 percentby weight, or from about 0.5 to about 6 percent by weight, all beingbased on total binder weight. In any of these embodiments, high Tgacrylic polymer is include in an amount from about 2 to about 25 percentby weight, or from about 5 to about 20 percent by weight, or from about5 to about 13 percent by weight, or from about 6 to about 10 percent byweight, based on total binder weight.

The binder may be any that is suitable for topcoat or basecoat coatingcompositions. The binder may be thermosettable, including those resinsthat are self-crosslinking, curable with a curing or crosslinking agent,or curable by exposure to actinic radiation such as UV or EB radiation,and crosslinking agents for such resins. The binder may include any oneor combination of a wide variety of resins or polymers. Nonlimitingexamples of suitable curable polymers include vinyl polymers such asacrylic polymers (poly(meth)acrylates) and modified acrylic polymersincluding those that are branched, grafted, and copolymers havingpolyester, polyether, or other blocks, polyesters, polyurethanes,polyurethanes prepared using macomonomers such as polyester diols,polyether diols, and polycarbonate diols; alkyds, epoxy resins,polycarbonates, polyamides, polyimides, polysiloxanes, alkyds, andunsaturated oligomers and resins, and mixtures thereof, all of which areknown in the art. In various embodiments, the curable polymer has groupsreactive with a crosslinker. Nonlimiting examples of polymer functionalgroups include carboxyl, hydroxyl, aminoplast functional groups, urea,carbamate, isocyanate, (blocked or unblocked), epoxy, cyclic carbonate,amine, aldehyde groups, thiol groups, hydrazide groups, activatedmethylene groups, and any combinations thereof that may be made in athermosettable polymer. In various embodiments the polymer functionalgroups are hydroxyl, primary carbamate, isocyanate, aminoplastfunctional groups, epoxy, carboxyl and mixtures thereof. In certainembodiments the polymer functional groups are hydroxyl, primarycarbamate, and mixtures thereof.

In one embodiment of the invention, the polymer is an acrylic polymer.In one or more embodiments, the acrylic polymer has a number averagemolecular weight of 500 to 20,000 and more specifically of 1500 to10,000. The number average molecular weight is determined by gelpermeation chromatography of a sample dissolved in tetrahydrofuran usingpolystyrene or poly(methyl methacrylate) standards. Such polymers arewell-known in the art, and can be prepared from monomers such as methylacrylate, methyl methacrylate, acrylic acid, methacrylic acid, ethylacrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate,isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butylmethacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butylacrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate,hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate, ethylhexylmethacrylate, 3,3,5-trimethylhexyl acrylate, 3,3,5-trimethylhexylmethacrylate, stearyl acrylate, stearyl methacrylate, lauryl acrylate orlauryl methacrylate, cycloalkyl acrylates and/or cycloalkylmethacrylates, such as cyclopentyl acrylate, cyclopentyl methacrylate,isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate andcyclohexyl methacrylate and vinylaromatic hydrocarbons, such asvinyltoluene, alpha-methylstyrene and styrene, as well as amides ornitriles of acrylic or methacrylic acid, vinyl esters and vinyl ethers.Any crosslinkable functional group, e.g., hydroxyl, amine, glycidyl,carbamate, and so on can be incorporated into the ester portion of theacrylic monomer. Nonlimiting examples of hydroxy-functional acrylicmonomers that can be used to form such polymers include hydroxyethylacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate,hydroxypropyl acrylate. Amino-functional acrylic monomers would includet-butylaminoethyl methacrylate and t-butylamino-ethylacrylate. Glycidylgroups may be incorporated by copolymerizing glycidyl methacrylate orallyl glycidyl ether, for example. Other acrylic monomers havingcrosslinkable functional groups in the ester portion of the monomer arealso within the skill of the art.

Modified acrylics can also be used as the film-forming curable polymerin the coating compositions. Such acrylics may be polyester-modifiedacrylics or polyurethane-modified acrylics, as is well known in the art.Polyester-modified acrylics modified with e-caprolactone are describedin U.S. Pat. No. 4,546,046 of Etzell et al, the disclosure of which isincorporated herein by reference. Polyurethane-modified acrylics arealso well known in the art. They are described, for example, in U.S.Pat. No. 4,584,354, the disclosure of which is incorporated herein byreference.

Polyesters can also be used as a binder resin in the coatingcomposition. Polyester resins may be formulated as acid-functional orhydroxyl-functional resins. The polyester may have an acid number offrom about 20 to about 100, or from about 20 to about 80, or from about20 to about 40 mg KOH per gram. In another embodiment, the polyester mayhave a hydroxyl number of from about 25 to about 300, or from about 25to about 150, or from about 40 to about 100 mg KOH per gram. The methodsof making polyester resins are well-known. Typically, a polyol componentand an acid and/or anhydride component or polymerizable derivative suchas a methyl ester are heated together, optionally with a catalyst, andusually with removal of the by-product water or methanol in order todrive the reaction to completion. The polyol component has an averagefunctionality of at least about two. The polyol component may containmono-functional, di-functional, tri-functional, and higher functionalalcohols. In one or more embodiments, diols are used, but when somebranching of the polyester is desired, higher functionality alcohols areincluded. Illustrative examples include, without limitation, alkyleneglycols and polyalkylene glycols such as ethylene glycol, propyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,3-butanediol,2,3-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol,1,9-nonanediol, 1,4-cyclohexane dimethanol,2,2,4-trimethyl-1,3-pentanediol, 2-methyl-2-ethyl-1,3-propanediol,2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and hydroxyalkylatedbisphenols. Optionally, a small amount of tri-functional, and higherfunctional alcohols may be used, such as glycerine, trimethylolpropane,trimethylolethane, or pentaerythritol. The acid and/or anhydridecomponent comprises compounds having on average at least two carboxylicacid groups and/or anhydrides or low alkyl (C1-C4, particularly methyl)esters of these. In one or more embodiments, dicarboxylic acids oranhydrides of dicarboxylic acids are used, but higher functional acidand anhydrides can be used when some branching of the polyester isdesired. Suitable polycarboxylic acid or anhydride compounds include,without limitation, those having from about 3 to about 20 carbon atoms.Illustrative examples of suitable compounds include, without limitation,phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalicacid, tetrahydrophthalic acid, pyromellitic acid, malonic acid, maleicacid, succinic acid, azeleic acid, glutaric acid adipic acid, azelaicacid, 1,4-cyclohexanedicarboxylic acid, dodecane-1,12-dicarboxylic acid,citric acid, trimellitic acid, and anhydrides thereof. Optionally,monocarboxylic acids such as octanoic acid, nonanoic acid, stearic acid,and cyclohexanoic acid; and hydroxycarboxylic acids such asdimethylolpropionic acid; as well as combinations of these compounds.

Polyurethanes having crosslinkable functional groups such as hydroxylgroups are also well known in the art. They are prepared by a chainextension reaction of a polyisocyanate (e.g., hexamethylenediisocyanate, isophorone diisocyanate, MDI, and any others of thosementioned above as useful in preparing the solid polyurea particles andcombinations of these) and a polyol (e.g., 1,6-hexanediol,1,4-butanediol, neopentyl glycol, and any others of those mentioned asuseful in preparing a polyester and combinations of these), as well asmacrodiols such as polyester diols, polyether diols, and polycarbonatediols. They can be provided with crosslinkable functional groups bycapping the polyurethane chain with an excess of diol, polyamine, aminoalcohol, or the like.

Carbamate functional polymers and oligomers can also be used as curablepolymer, especially those having at least one primary carbamate group.

Carbamate functional examples of the curable polymer used in the coatingcompositions can be prepared in a variety of ways. For example, andusing the case of an acrylic polymer, one way to prepare such polymersis to prepare a monomer, e.g., an acrylic monomer, having carbamatefunctionality in the ester portion of the monomer. Such monomers arewell known in the art and are described, for example in U.S. Pat. Nos.3,479,328, 3,674,838, 4,126,747, 4,279,833, and 4,340,497, 5,356,669,and WO 94/10211, the disclosures of which are incorporated herein byreference. One method of synthesis involves reaction of a hydroxy esterwith urea to form the carbamyloxy carboxylate (i.e., carbamate-modifiedacrylic). Another method of synthesis reacts an α,β-unsaturated acidester with a hydroxy carbamate ester to form the carbamyloxycarboxylate. Yet another technique involves formation of a hydroxyalkylcarbamate by reacting a primary or secondary amine or diamine with acyclic carbonate such as ethylene carbonate. The hydroxyl group on thehydroxyalkyl carbamate is then esterified by reaction with acrylic ormethacrylic acid to form the monomer. Other methods of preparingcarbamate-modified acrylic monomers are described in the art, and can beutilized as well. The acrylic monomer can then be polymerized along withother ethylenically unsaturated monomers, if desired, by techniques wellknown in the art.

An alternative route for preparing the curable polymer of the binder isto react an already-formed polymer such as an acrylic polymer, polyesterpolymer, or polyurethane polymer with another component to form acarbamate-functional group appended to the polymer backbone, asdescribed in U.S. Pat. No. 4,758,632. One technique for preparing suchpolymers involves thermally decomposing urea (to give off ammonia andHNCO) in the presence of a hydroxy-functional acrylic polymer to form acarbamate-functional polymer. Another technique involves reacting thehydroxyl group of a hydroxyalkyl carbamate with the isocyanate group ofan isocyanate-functional polymer to form the carbamate-functionalpolymer. Isocyanate-functional acrylics are known in the art and aredescribed, for example in U.S. Pat. No. 4,301,257, the disclosure ofwhich is incorporated herein by reference. Isocyanate vinyl monomers arewell known in the art and include unsaturated m-tetramethyl xyleneisocyanate (sold by American Cyanamid as TMI®). Isocyanate-functionalpolyurethanes may be formed by using an equivalent excess ofdiisocyanate or by end-capping a hydroxyl-functional prepolymer with apolyisocyanate. Yet another technique is to react the cyclic carbonategroup on a cyclic carbonate-functional acrylic with ammonia in order toform the carbamate-functional acrylic. Cyclic carbonate-functionalacrylic polymers are known in the art and are described, for example, inU.S. Pat. No. 2,979,514, the disclosure of which is incorporated hereinby reference. Another technique is to transcarbamylate ahydroxy-functional polymer with an alkyl carbamate. A more difficult,but feasible way of preparing the polymer would be to trans-esterifywith a hydroxyalkyl carbamate.

The binder of the coating compositions may further comprise acrosslinker. Crosslinkers may be used in amounts of from 10 to 60%,generally from 15 to 55%, or from 25 to 50%, all based on the totalbinder of the coating composition.

In certain specific embodiments, the reaction between the crosslinkerand polymer to form irreversible linkages. Examples of functional group“pairs” producing thermally irreversible linkages are hydroxy/isocyanate(blocked or unblocked), hydroxy/epoxy, carbamate/aminoplast,carbamate/aldehyde, acid/epoxy, amine/cyclic carbonate, amine/isocyanate(blocked or unblocked), urea/aminoplast, and the like. Nonlimitingexamples of crosslinker binder resins include aminoplasts, blocked orunblocked polyisocyanates, polyepoxides, polycarboxylic acid oranhydride compounds, oligomers, or polymers, and polyurea compounds oroligomers.

The high solids coating composition in certain embodiments includes anaminoplast as a crosslinker. An aminoplast for purposes of the inventionis a material obtained by reaction of an activated nitrogen with a lowermolecular weight aldehyde, optionally further reacted with an alcohol(in specific embodiments, a mono-alcohol with one to four carbon atoms)to form an ether group. In one or more embodiments, examples ofactivated nitrogens are activated amines such as melamine,benzoguanamine, cyclohexylcarboguanamine, and acetoguanamine; ureas,including urea itself, thiourea, ethyleneurea, dihydroxyethyleneurea,and guanylurea; glycoluril; amides, such as dicyandiamide; and carbamatefunctional compounds having at least one primary carbamate group or atleast two secondary carbamate groups.

The activated nitrogen is reacted with a lower molecular weightaldehyde. In one or more embodiments, the aldehyde may be selected fromformaldehyde, acetaldehyde, crotonaldehyde, benzaldehyde, or otheraldehydes used in making aminoplast resins, although formaldehyde andacetaldehyde, especially formaldehyde. The activated nitrogen groups areat least partially alkylolated with the aldehyde, and may be fullyalkylolated; specifically the activated nitrogen groups are fullyalkylolated. The reaction may be catalyzed by an acid, e.g. as taught inU.S. Pat. No. 3,082,180, the contents of which are incorporated hereinby reference.

The alkylol groups formed by the reaction of the activated nitrogen withaldehyde may be partially or fully etherified with one or moremonofunctional alcohols. Suitable examples of the monofunctionalalcohols include, without limitation, methanol, ethanol, propanol,isopropanol, butanol, isobutanol, tert-butyl alcohol, benzyl alcohol,and so on. In one or more embodiments, monofunctional alcohols havingone to four carbon atoms and mixtures of these are used. Theetherification may be carried out, for example, by the processesdisclosed in U.S. Pat. Nos. 4,105,708 and 4,293,692, the disclosures ofwhich are incorporated herein by reference.

The aminoplast may be at least partially etherified, and in variousembodiments the aminoplast is fully etherified. For example, theaminoplast compounds may have a plurality of methylol and/or etherifiedmethylol, butylol, or alkylol groups, which may be present in anycombination and along with unsubstituted nitrogen hydrogens. Onenonlimiting example of a fully etherified melamine-formaldehyde resin ishexamethoxymethyl melamine. Aminoplast crosslinkers may be used ascrosslinkers for carbamate, terminal urea, and hydroxyl containingpolymers.

The high solids curable coating composition in certain embodimentsincludes a polyisocyanate or blocked polyisocyanate crosslinker. Usefulpolyisocyanate crosslinkers include, without limitation, isocyanurates,biurets, allophanates, uretdione compounds, and isocyanate-functionalprepolymers such as the reaction product of one mole of a triol withthree moles of a diisocyanate. The polyisocyanate may be blocked withlower alcohols, oximes, or other such materials that volatilize atcuring temperature to regenerate the isocyanate groups.

An isocyanate or blocked isocyanate is may be used in a 0.1-1.1equivalent ratio, or in an equivalent ratio of 0.5-1.0 to eachequivalent of functional groups reactive with it available from thecrosslinkable binder resin.

Epoxide-functional crosslinkers may be used with carboxyl- oramine-functional crosslinkable resins. Illustrative examples ofepoxide-functional crosslinkers are all known epoxide-functionalpolymers and oligomers. Nonlimiting examples of epoxide-functionalcrosslinking agents are polyglycidyl ethers, polyglycidyl esters,glycidyl methacrylate polymers, and isocyanurate-containing,epoxide-functional materials such as trisglycidyl isocyanurate and thereaction product of glycidol with an isocyanate-functional isocyanuratesuch as the trimer of isophorone diisocyanate (IPDI).

The high solids coating composition may include a catalyst to enhancethe rate of the cure reaction. For example, especially when monomericmelamines are used as a curing agent, a strong acid catalyst may beutilized to enhance the cure reaction. Such catalysts are well-known inthe art and include, without limitation, p-toluene sulfonic acid,dinonylnaphthalene disulfonic acid, dodecylbenzenesulfonic acid, phenylacid phosphate, monobutyl maleate, butyl phosphate, and hydroxyphosphate ester. Strong acid catalysts are often blocked, e.g. with anamine. For the reaction of polyisocyanates with suitable curable binderresin functionalities, suitable catalysts include tin compounds such asdibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin oxide,tertiary amines, zinc salts, and manganese salts. Reactions betweenepoxide and carboxyl groups may be catalyzed with tertiary amines orquaternary ammonium salts (e.g., benzyldimethylamine,dimethylaminocyclohexane, triethylamine, N-methylimidazole, tetramethylammonium bromide, and tetrabutyl ammonium hydroxide), tin and/orphosphorous complex salts (e.g., (CH3)3 SNI, (CH3)4 PI,triphenylphosphine, ethyltriphenyl phosphonium iodide, tetrabutylphosphonium iodide) and so on.

The high solids coating compositions include one or more organicsolvents. Nonlimiting examples of suitable solvents include aromatichydrocarbons, ketones, esters, glycol ethers, and esters of glycolethers. Specific examples include, without limitation, methyl ethylketone, methyl isobutyl ketone, m-amyl acetate, ethylene glycol butylether and ethylene glycol monobutyl ether acetate, propylene glycolmonomethyl ether and propylene glycol monomethyl ether acetate, xylene,ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol,N-methyl pyrrolidone, N-ethyl pyrrolidone, Aromatic 100, Aromatic 150,naphtha, mineral spirits, butyl glycol, and so on.

The high solids coating composition may optionally include furtherrheology control agents, including high molecular weight mixed celluloseesters, such as CAB-381-0.1, CAB-381-20. CAB-531-1, CAB-551-0.01, andCAB-171-15S (available from Eastman Chemical Company, Kingsport, Tenn.),which may be included in amounts of up to about 5 wt. %, or from about0.1 to about 5 wt. %, or from about 1.5 to about 4.5 wt. %, based ontotal binder weight. Further examples include microgel rheology controlagents such as crosslinked acrylic polymeric microparticles, which maybe included in amounts of up to about 5 wt. % of total binder weight;wax rheology control agents such as polyethylene waxes including acrylicacid-modified polyethylene wax (e.g., Honeywell A-C® PerformanceAdditives), poly(ethylene-vinyl acetate) copolymers, and oxidizedpolyethylenes, which may be included in amounts of up to about 2 wt. %on total binder weight; and fumed silicas, which may be included inamounts of up to about 10 wt. % on total binder weight or from about 3to about 12 wt. % on total binder weight.

Additional agents, for example hindered amine light stabilizers,ultraviolet light absorbers, anti-oxidants, surfactants, stabilizers,wetting agents, adhesion promoters, etc. may be incorporated into thecoating composition. Such additives are well-known and may be includedin amounts typically used for coating compositions.

Nonlimiting examples of special effect pigments that may be utilized inbasecoat and monocoat topcoat coating compositions include metallic,pearlescent, and color-variable effect flake pigments. Metallic(including pearlescent, and color-variable) topcoat colors are producedusing one or more special flake pigments. Metallic colors are generallydefined as colors having gonioapparent effects. For example, theAmerican Society of Testing Methods (ASTM) document F284 definesmetallic as “pertaining to the appearance of a gonioapparent materialcontaining metal flake.” Metallic basecoat colors may be produced usingmetallic flake pigments like aluminum flake pigments, coated aluminumflake pigments, copper flake pigments, zinc flake pigments, stainlesssteel flake pigments, and bronze flake pigments and/or using pearlescentflake pigments including treated micas like titanium dioxide-coated micapigments and iron oxide-coated mica pigments to give the coatings adifferent appearance (degree of reflectance or color) when viewed atdifferent angles. Metal flakes may be cornflake type, lenticular, orcirculation-resistant; micas may be natural, synthetic, oraluminum-oxide type. Flake pigments do not agglomerate and are notground under high shear because high shear would break or bend theflakes or their crystalline morphology, diminishing or destroying thegonioapparent effects. The flake pigments are satisfactorily dispersedin a binder component by stirring under low shear. The flake pigment orpigments may be included in the high solids coating composition in anamount of about 0.01 wt. % to about 0.3 wt. % or about 0.1 wt. % toabout 0.2 wt. %, in each case based on total binder weight.

Nonlimiting examples of commercial flake pigments include PALIOCROME®pigments, available from BASF Corporation.

Nonlimiting examples of other suitable pigments and fillers that may beutilized in basecoat and monocoat topcoat coating compositions includeinorganic pigments such as titanium dioxide, barium sulfate, carbonblack, ocher, sienna, umber, hematite, limonite, red iron oxide,transparent red iron oxide, black iron oxide, brown iron oxide, chromiumoxide green, strontium chromate, zinc phosphate, silicas such as fumedsilica, calcium carbonate, talc, barytes, ferric ammonium ferrocyanide(Prussian blue), and ultramarine, and organic pigments such asmetallized and non-metallized azo reds, quinacridone reds and violets,perylene reds, copper phthalocyanine blues and greens, carbazole violet,monoarylide and diarylide yellows, benzimidazolone yellows, tolylorange, naphthol orange, and so on. In one or more embodiments, thepigment or pigments are dispersed in a resin or polymer or with apigment dispersant, such as binder resins of the kind already described,according to known methods. In general, the pigment and dispersingresin, polymer, or dispersant are brought into contact under a shearhigh enough to break the pigment agglomerates down to the primarypigment particles and to wet the surface of the pigment particles withthe dispersing resin, polymer, or dispersant. The breaking of theagglomerates and wetting of the primary pigment particles are importantfor pigment stability and color development. Pigments and fillers may beutilized in amounts typically of up to about 40% by weight, based ontotal weight of the coating composition.

The combination of rheology control agents is particularly when used ina monocoat topcoat or basecoat coating composition containing a flakepigment. A monocoat topcoat coating composition is a pigmented coatingcomposition applied as a final finishing coating layer that provides adesired color and gloss for the finish. Basecoat coating compositionsare used with clearcoat coating compositions to provide a compositetopcoat in which an underlying layer of basecoat provides a desiredcolor and an overlying layer of clearcoat provides a desired gloss forthe finish.

The particular solids for the high solids basecoats and monolayertopcoats varies with the color and color strength due to the effect ofpigment loading and type of pigment on viscosity. Generally, thedisclosed basecoats may have about 40 wt. % to about 55 wt. %,nonvolatile content, and typically may have about 45 wt. % to about 50wt. % nonvolatile content, as determined by ASTM Test Method D2369, inwhich the test sample is heated at 110° C. (230° F.) for 60 minutes.

In general, a substrate may be coated by applying a primer layer,optionally curing the primer layer; then applying a basecoat layer and aclearcoat layer, typically wet-on-wet, and curing the applied layers andoptionally curing the primer layer along with the basecoat and clearcoatlayers if the primer layer is not already cured, or then applying amonocoat topcoat layer and curing the monocoat topcoat layer, againoptionally curing the primer layer along with the basecoat and clearcoatlayers if the primer layer is not already cured. The cure temperatureand time may vary depending upon the particular binder componentsselected, but typical industrial and automotive thermoset compositionsprepared as we have described may be cured at a temperature of fromabout 105° C. to about 175° C., and the length of cure is usually about15 minutes to about 60 minutes.

The coating composition can be coated on a substrate by spray coating.Electrostatic spraying is a preferred method. The coating compositioncan be applied in one or more passes to provide a film thickness aftercure of a desired thickness, typically from about 10 to about 40 micronsfor primer and basecoat layers and from about 20 to about 100 micronsfor clearcoat and monocoat topcoat layers.

The coating composition can be applied onto many different types ofsubstrates, including metal substrates such as bare steel, phosphatedsteel, galvanized steel, or aluminum; and non-metallic substrates, suchas plastics and composites. The substrate may also be any of thesematerials having upon it already a layer of another coating, such as alayer of an electrodeposited primer, primer surfacer, and/or basecoat,cured or uncured.

The substrate may be first primed with an electrodeposition(electrocoat) primer. The electrodeposition composition can be anyelectrodeposition composition used in automotive vehicle coatingoperations. Non-limiting examples of electrocoat compositions includethe CATHOGUARD® electrocoating compositions sold by BASF Corporation,such as CATHOGUARD® 500. Electrodeposition coating baths usuallycomprise an aqueous dispersion or emulsion including a principalfilm-forming epoxy resin having ionic stabilization (e.g., salted aminegroups) in water or a mixture of water and organic cosolvent. Emulsifiedwith the principal film-forming resin is a crosslinking agent that canreact with functional groups on the principal resin under appropriateconditions, such as with the application of heat, and so cure thecoating. Suitable examples of crosslinking agents, include, withoutlimitation, blocked polyisocyanates. The electrodeposition coatingcompositions usually include one or more pigments, catalysts,plasticizers, coalescing aids, antifoaming aids, flow control agents,wetting agents, surfactants, UV absorbers, HALS compounds, antioxidants,and other additives.

In one or more embodiments, the electrodeposition coating composition isapplied to a dry film thickness of 10 to 35 μm. After application, thecoated vehicle body is removed from the bath and rinsed with deionizedwater. The coating may be cured under appropriate conditions, forexample by baking at from about 275° F. to about 375° F. (about 135° C.to about 190° C.) for between about 15 and about 60 minutes.

The invention is further described in the following examples. Theexample is merely illustrative and does not in any way limit the scopeof the invention as described and claimed. All parts are parts by weightunless otherwise noted.

EXAMPLES

These methods were used in testing the examples that follow:

To assess metal control, the examples and comparative examples werecompared visually and by measurement of lightness at particular angles.A panel made with a coating having effective metal control, or metallicappearance, has a bright (light) “flash” angle and dark “flop” angle.Visually, a painted panel is viewed in a way to see the directreflection of incident light then titled very slightly; this is calledthe flash angle. The painted panel is then viewed at a much steeperangle, close to a right angle from the angle of direct reflection, werethe coating should appear dark; this is called the flop angle. Ameasurement of lightness at an angle from the plane of the coating layeris determined with a multi-angle spectrophotometer or colorimeter(typically used for OEM automotive coatings). In the spectrophotometer,the illumination of the sample is 45° away from the line that isperpendicular to the surface of the panel. At an illumination angle of45° the gloss (the surface reflection) occurs at the equal and oppositeangle of reflection (also referred to as the specular angle), or −45°.The spectrophotometer has detectors placed at various locationsdescribed relative to the specular angle. In testing the examples thesedetectors are placed from 15° through 75° from the specular angle.Standard color tolerances for light metallic automotive topcoat colorswere used. The measurements are recorded as a change in lightness fromthe lightness that is measured at that angle for a control panelprepared using the commercial product Shear Silver R99AW010F Basecoat,available from BASF Corporation, Metallic appearance is judged bothvisually and by comparing the differences in lightness measured atangles of 15° and 75°. When viewing the face of the coated panelstraight on, the coating should be lightest and when viewed atincreasingly oblique angles as the panel is moved away from the view to90° angle from its original face-on position the coating should becomedarker and darker. Metallic appearance is judged by the brightness ofthe face (lighter is better) with increasing darkness to the furthestviewable angle from the face (darker is better), with a greater changein face lightness to flop darkness providing the greatest travel ormetallic effect. Any increase in lightness with increasing angle of flopis undesirable and detracts from the visual metallic appearance, even ifthe coating becomes darker again at a still greater angle. Visually, asa panel is viewed more and more obliquely the coating should get darkerand darker, not go through a As compared to the control panel, a <dL>measured at 15° greater than 0 indicates a lighter face and a <dL>measured at 75° less than 0 indicates a darker flop. A lighter value at15° and a darker flop at 75° generally indicates better travel andbetter metallic appearance, unless the coating has the undesirableeffect of increasing in lightness at an angle between 15° and 75°, whichis undesirable. This latter effect can be determined by visually viewingthe panel or by measuring lightness at intervening angles.

Nonvolatiles by weight, as determined by ASTM Test Method D2369, inwhich the test sample is heated at 110° C. (230° F.) for 60 minutes.

Example 1 and Comparative Examples A-C

Basecoat coating compositions were prepared using the ingredients shownin Table 1. The prepared coating compositions were reduced to a sprayviscosity of 21 second as measured with a Fisher #2 cup and thenonvolatile content of each was determined by ASTM Test Method D2369, inwhich the test sample is heated at 110° C. (230° F.) for 60 minutes.These values are recorded in Table 2.

TABLE 1 Comp. Comp. Comp. Example Example Example Example Component 1,Weight A, Weight B, Weight C, Weight 20% by weight of CAB 4.485 0.0004.554 0.000 381-0.5¹ in butyl acetate High T_(g) Acrylic² 10.165 0.00010.321 13.276 butyl acetate 5.214 5.405 5.183 5.459 Aromatic 100 5.3945.592 5.362 5.648 Monomeric, fully- 14.069 16.009 14.286 15.619alkylated melamine- formaldehyde resin Additive Package 1.114 1.2681.131 1.236 Dispersion of 13% 8.117 9.237 8.242 9.011 weight fumedsilica in hydroxyl-functional acrylic polymer³ Dispersion with about8.375 9.529 8.504 9.298 63% by weight of filler pigment and about 14% byweight hydroxyl- functional acrylic polymer³ Hydroxyl-functional 0.0009.070 9.327 10.197 acrylic polymer³ SETAL 82166 SS-64⁴ 10.764 12.2480.000 0.000 blocked acid catalyst 1.810 2.054 1.838 2.010 Dispersion of31.5% 3.104 3.533 3.152 3.446 by weight of aluminum (type 1) inhydroxyl-functional acrylic polymer⁴ Dispersion of 29.93% 13.068 14.87013.269 14.508 by weight of aluminum (type 2) in hydroxyl-functionalacrylic polymer⁴ ethanol 1.044 1.840 2.445 1.880 Aromatic 100 13.2769.345 12.387 8.412 ¹Obtained from Eastman Chemical Company (highmolecular weight cellulose acetate butyrate polymer, butyryl content of37 wt. %, acetyl content of 13 wt. %, hydroxyl content of 1.5 wt. %,T_(g) 130° C., melting point 155-165° C., viscosity 1.9 poise asdetermined by ASTM Method D1343 in the solution described as Formula A).²Polymerization product of 2.27 parts by weight 2-ethylhexyl acrylate,5.68 parts by weight methyl methacrylate, 12.10 parts by weighthydroxymethyl methacrylate, 5.68 parts by weight styrene, 73.73 parts byweight cyclohexyl methacrylate, 50% nonvolatile in a mixture of methylethyl ketone and n-butyl acetate, having a theoretical T_(g) of 70° C.as determined using the Fox equation and a Tg of 65.1 as measured byDSC, a hydroxyl number of 54 mg. KOH/gm nonvolatiles., and a numberaverage molecular weight of 6650 daltons. ³75% nonvolatiles (NV) inAromatic 100. The same hydroxyl-functional acrylic polymer is used ineach case. ⁴SETAL 10-1821, obtained form Nuplex Resins LLC (slightlybranched polyester polyol with 5.4% OH on nonvolatiles (NV), containing2.5% by weight solid polyurea particles)

Preparation and Testing of Coated Panels Using Example 1 and ComparativeExamples A, B, and C

The silver basecoat compositions of Example 1 and Comparative ExamplesA, B, and C were individually applied onto 4-inch-by-twelve-inch primedsteel panels, two for each of the example basecoats, by an automated,electrostatic application in two “coats” or application passes (one coatbell, one coat Sames air atomized), with a short pause or flash betweencoats. The wet basecoat was allowed to flash (four-minute flash at 170°F. (76.7° C.)), then a commercial clearcoat (UREGLOSS® R10CG060B,available from BASF Corporation) was applied over the basecoat on eachpanel in two coats with a short flash between coats and after the secondand least coat. The basecoat coating layer and the clearcoat coatinglayer were then cured together in a forced air oven for 20 minutes at265° F. (129.4° C.). One of the two panels prepared for each basecoatexample was cured in a horizontal position in the oven and the second ofthe two panels was cured in an upright, near-vertical position in theoven.

Testing results for each panel prepared with one of the basecoatcompositions of Example 1 and Comparative Examples A, B, and C are shownin the following table.

TABLE 2 Nonvola- Orientation Basecoat tiles by of panel during <dL> at15° <dL> at 75° Example weight cure in oven (target: >0) (target: <0)Control 43.07 Horizontal 0 0 Example 1 44.97 Horizontal 0.67 −0.84Comparative 50.30 Horizontal −4.74 6.02 Example A Comparative 45.81Horizontal −3.52 4.18 Example B Comparative 48.23 Horizontal −5.40 6.55Example C Control 43.07 Vertical 0 0 Example 1 44.97 Vertical 1.36 −1.52Comparative 50.30 Vertical −3.98 5.71 Example A Comparative 45.81Vertical −4.91 6.07 Example B Comparative 48.23 Vertical 0.07 −0.11Example C

The results in Table 2 demonstrate that Example 1, the example of theinventor having a combination of solid polyurea particles and an acrylicpolymer having a number average molecular weight of from about 2000 toabout 8000 and a glass transition temperature of from about 50 to about120° C., provides an improvement in metallic appearance relative to thecontrol. This could not have been expected based on the much poorerresults obtained from Comparative Examples A (without the high Tgacrylic) B (without the urea crystals), and C (without the urea crystalsand without the CAB 381-0.5).

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A high solids coating composition comprising (a)a thermosetting curable or crosslinking binder selected from the groupconsisting of polyesters; polyurethanes; polyurethanes prepared usingmacomonomers selected from polyester diols, polyether diols, andpolycarbonate diols; alkyds; epoxy resins; polycarbonates; polyamides;polyimides; polysiloxanes; and unsaturated oligomers and resins; andmixtures thereof, (b) from about 0.1 to about 10 wt. % based on bindersolids of solid polyurea particles prepared by reacting a reactionmixture of a polyisocyanate and an amino reactant comprising a primaryor secondary monoamine that optionally has a hydroxyl or ether group orboth, and (c) from about 2 to about 25 wt. % based on binder solids ofan acrylic polymer having a number average molecular weight of fromabout 2000 to about 8000 and a glass transition temperature of fromabout 65 to about 120° C., wherein the acrylic polymer comprisescycloaliphatic monomer units.
 2. The high solids coating compositionaccording to claim 1, comprising a flake pigment.
 3. The high solidscoating composition according to claim 1, further comprising a rheologycontrol agent selected from a cellulose mixed ester other than a lowmolecular weight cellulose mixed ester, crosslinked acrylic polymericmicroparticles, an inorganic phyllosilicate, a fumed silica, orcombinations thereof.
 4. The high solids coating composition accordingto claim 1, wherein the reaction mixture further comprises water, apolyamine, a monoisocyanate, or a combination thereof.
 5. The highsolids coating composition according to claim 1, wherein thepolyisocyanate comprises an aliphatic or homocyclic diisocyanatecontaining 6-9 carbon atoms or wherein the polyisocyanates is selectedfrom the group consisting of cyclohexyl-1,4-diisocyanate, toluenediisocyanates, hexamethylene diisocyanate, isocyanurates of these, andcombinations of these.
 6. The high solids coating composition accordingto claim 1, wherein the amino reactant comprises a member selected fromthe group consisting of benzylamine, ethylamine, n-propylamine,isopropylamine, n-butylamine, isobutylamine, tert-butylamine,2-aminoethanol, 1-aminoethanol, 2-aminopropanol, 3-aminopropanol,1-amino-2-propanol, 2-amino-2-methyl propanol, 2-methoxyethylamine,2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxymethylpropylamine,and combinations of these.
 7. The high solids coating compositionaccording to claim 1, wherein the solid polyurea particles are preparedby the reaction of the mixture in at least one of an acrylic, polyester,or polyurethane resin.
 8. The high solids coating composition accordingto claim 1, wherein the acrylic polymer has a weight average molecularweight of from about 5000 to about 25,000 or a polydispersity of fromabout 2.0 to about 4, or both.
 9. The high solids coating compositionaccording to claim 1, wherein the acrylic polymer has active hydrogenfunctionality.
 10. The high solids coating composition according toclaim 1, wherein the cycloaliphatic monomer units are included in theacrylic polymer in amounts of from about 45% to about 85% by weightbased on acrylic polymer weight.
 11. The high solids coating compositionaccording to claim 1, having at least about 40 wt. %, nonvolatilecontent.
 12. A method of coating a substrate, comprising spray applyingthe high solids coating composition according to claim 1 in a layer on asubstrate, then curing the applied coating composition to produce acured coating on the substrate.
 13. A method of coating a substrate,comprising applying at least one primer coating composition to form aprimer layer, at least one basecoat composition to form a basecoatlayer, and at least one clearcoat composition to form a clearcoat layerto a substrate; wherein the basecoat composition is applied when theprimer layer is uncured; wherein the basecoat composition is the highsolids coating composition according to claim
 1. 14. A method of coatinga substrate, comprising applying at least one primer coating compositionto form a primer layer, at least one basecoat composition to form abasecoat layer, and at least one clearcoat composition to form aclearcoat layer to a substrate; wherein the clearcoat composition isapplied when the basecoat layer is uncured; wherein the basecoatcomposition is the high solids coating composition according to claim 1.15. A method of coating a substrate, comprising applying at least oneprimer coating composition to form a primer layer, at least one basecoatcomposition to form a basecoat layer, and at least one clearcoatcomposition to form a clearcoat layer to a substrate; where the basecoatcomposition is applied when the primer layer is uncured and theclearcoat composition is applied when the basecoat layer is uncured; andwherein the basecoat composition is the high solids coating compositionaccording to claim
 1. 16. A method of coating a substrate, comprisingapplying the high solids coating composition according to claim 1 as amonocoat topcoat layer on a substrate.
 17. A method of improvingrheology control during a process of applying a high solids coatingcomposition in a layer on a substrate and curing the applied layer, themethod comprising including in the high solids coating composition fromabout 0.1 to about 10 wt. % based on binder solids of solid polyureaparticles prepared by the reaction of a mixture of a polyisocyanate andan amino reactant comprising a primary or secondary monoamine thatoptionally has a hydroxyl or ether group or both, and from about fromabout 2 to about 25 wt. % based on binder solids of an acrylic polymerhaving a number average molecular weight of from about 2000 to about8000 and a glass transition temperature of from about 65 to about 120°C., wherein the acrylic polymer comprises cycloaliphatic monomer units,wherein the high solids coating composition comprises a thermosettingcurable or crosslinkable binder selected from the group consisting ofpolyesters; polyurethanes; polyurethanes prepared using macomonomersselected from polyester diols, polyether diols, and polycarbonate diols;alkyds; epoxy resins; polycarbonates; polyamides; polyimides;polysiloxanes; and unsaturated oligomers and resins; and mixturesthereof.
 18. The method according to claim 17, wherein the high solidscoating composition further comprises a member selected from the groupconsisting of an additional cellulose mixed ester other than a lowmolecular weight cellulose mixed ester, crosslinked acrylic polymericmicroparticles, an inorganic phyllosilicate, a fumed silica, andcombinations thereof.